DE102018211639A1 - Device and method for producing particles - Google Patents

Abstract

The invention relates to a device (PR) for producing particles (P), in particular fine particles such as nanoscale or nanocrystalline particles (P), for example with an average particle size of 10 nm to a few millimeters, from at least one raw material (RM). with at least one burner (1) and a combustion chamber (2) adjoining the burner (1) for generating a pulsating hot gas flow (HGS), - with a reaction chamber section (5) downstream of a material feed and - with at least one reaction chamber section (5) Indirectly downstream separation device (7) for separating formed particles (P) from the hot gas stream (HGS), - the separation device (7) comprising a filter arrangement (8), the filter area of which can be variably adjusted. The invention further relates to a method for producing particles (P).

Description

The invention relates to a device for producing particles, in particular fine-particle particles, such as nanoscale or nanocrystalline particles.

The invention further relates to a process for the production of particles, in particular of finely divided particles, such as nanoscale or nanocrystalline particles.

Such particles typically have an average grain size of 10 nm to a few millimeters.

Atoms or molecules that are part of a surface have different electronic and chemical properties than their atoms or molecules inside the material. The smaller a particle is, the higher its proportion of surface atoms. Correspondingly, very fine-particle materials, particularly nanoparticles, can have completely different mechanical, electronic, chemical or optical properties than chemically and mineralogically identical larger particles and therefore make them particularly interesting for specific applications.

The following manufacturing processes have essentially been established for the production of fine-particle powders; chemical production in solutions (e.g. sol-gel method), production in plasma or production from the gas phase (aerosol process). Depending on the area of application of the nanoparticles, a precisely defined and narrow particle size distribution is usually required. Depending on the chemical nature of the desired nanoparticles, one or the other method is more suitable to achieve a good result. In most cases, processes in solution or processes of self-organization provide the best results, but are difficult or not feasible on an industrial scale.

From the WO 02/072471 A2 or from the DE 10 2004 044 266 A1 pulsation reactors for the production of finely divided powders are known.

The invention is based on the object of specifying an improved device and an improved method for producing particles, in particular of finely divided, for example nanoscale or nanocrystalline, particles.

With regard to the device, the object is achieved according to the invention by the features specified in claim 1 and with respect to the method by the features specified in claim 9.

Advantageous embodiments of the invention are the subject of the dependent claims.

The device for producing particles, in particular of finely divided, such as nanoscale or nanocrystalline particles, for example with an average particle size of 10 nm to a few millimeters, from at least one raw material comprises at least one burner and a combustion chamber adjoining the burner for generating a pulsating hot gas stream. Furthermore, the device comprises a reaction chamber section, for example a resonance tube, downstream of a material task for the feed of the raw material and a separator device, at least indirectly, downstream of the reaction chamber section, for example via an outlet line, for separating particles formed from the hot gas stream, the separating device comprising a filter arrangement, the filter area of which is variable is adjustable.

By means of the device it is possible to adapt the filter surface on which the manufactured particles separate, and thus to adapt the separation of the particles to an occupancy and / or a volume of the hot gas flow. In the present case, an occupancy is understood to mean a layer of particles which collects on a filter medium before it falls off from the filter medium into a collecting container due to its own weight and a blast of compressed air.

With the device it is possible, for example, to set a relatively small filter area with a low loading and / or low volume flow and thus to generate less material losses through a minimum occupancy. As a result, a large number of separated particles per filter area can be kept large, so that particles can be discharged from the separating device particularly quickly after a first loading, in particular using gravity. Furthermore, an amount of gas, for example air, used for example in the separator to support the discharge of the particles can be kept small, and the separator can thus be designed inexpensively.

With a high load and / or high volume flow, on the other hand, a relatively large filter area can be set, so that a high discharge quantity of the particles can be achieved without a differential pressure across the filter increasing to an extent that is not permissible for the process.

Nanoscale particles that are produced in the device described above include, in particular, particles in the nano range according to DIN SPEC 1121 (DIN ISO / TS 27687 ) understood the for example, have grain or particle sizes in the range from 10 nm to 120 nm, in particular in the range from 20 nm to 100 nm, for example from 40 nm to 80 nm. Nanocrystalline particles that are produced in the device described above are understood to mean, in particular, particles whose grain is formed from several small crystals and a grain or particle size of a few millimeters, in particular less than 8 mm, in particular less than 5 mm or 3 mm, exhibit. Finely divided particles can also be understood to mean nanocrystalline particles with a particle size of <20 μm. Furthermore, it can be understood that nanoparticles, in particular so-called nanoscale particles, are related to particle sizes in the nano range, whereby nanocrystalline particles can have a larger particle size in comparison. The nanocrystalline particles are characterized, for example, by a polycrystalline structure in which the crystals can have size arrangements in the nano range. These substances can also have differentiated properties. In particular, both types of particles can be generated depending on the input material.

The raw material is in particular given as a solid, for example as an impregnated solid. For example, it can be a finely divided powder with or without a coating. Alternatively, the raw material can be applied in the form of a solution or suspension. The raw material material is introduced as a solution or suspension, for example into the combustion chamber.

A reaction space is understood to mean, in particular, that plant or reactor space volume, such as, for example, tube, container and / or line volume, from the point at which the raw material is fed to the cooling of the material before the particles are separated or filtered.

In one possible embodiment of the device, the filter arrangement comprises a plurality of filter elements.

In a further possible embodiment of the device, a number of filter elements that are fluidically connected to the hot gas flow can be variably adjusted in order to adjust the filter surface in a simple manner.

For this variable setting, the device according to a possible further development comprises at least one switching element for establishing or blocking the fluidic connection between the filter elements and the hot gas flow. This switching element is designed, for example, such that the fluidic connection can be established or blocked during operation of the device. It is therefore possible that a filter element is first used for filtering or separation. You can then switch to another filter element and the fluidic connection to the filter element used initially is blocked. This enables the filter element initially used to be emptied and / or cleaned without having to interrupt the operation of the device. It is also possible to add or block filter elements to the filter surface when the load and / or the volume flow are changed by means of the switching element during operation of the device, and thus to adapt the filter surface to a current load and / or a current volume flow without interrupting operation.

According to a possible embodiment of the device, the separating device comprises a plurality of filter connections for receiving at least one filter element each, the filter connections each comprising at least one opening for inserting and removing the at least one filter element. This configuration makes it possible to adapt the filter surface to the respective load and / or the respective volume flow by adding or removing filter elements from the filter connections.

According to a development of the device, it comprises a plurality of closure elements for closing the openings and for blocking a flow through the filter elements through the loaded hot gas stream. Flow of empty filter connections or filter connections equipped with filter elements with the hot gas flow can thus be avoided in a simple manner.

In one possible embodiment of the device, the filter elements are designed as bag filters, which are particularly easy to handle and regenerate.

In one possible development of the device, the filter elements are designed to be temperature-resistant.

In the process for the production of particles, in particular of finely divided, such as nanoscale or nanocrystalline particles, for example with an average particle size of 10 nm to a few millimeters, from at least one raw material material by means of the above-mentioned device, depending on a load and / or a volume of the hot gas flow, the filter area of the filter arrangement of the separating device is variably set.

With the method it is possible, for example, to set a relatively small filter area with a low loading and / or low volume flow. As a result, a large number of separated particles per filter area can be kept large, so that particles can be discharged from the separating device particularly quickly after a first loading, in particular using gravity. At the same time, an amount of gas, for example air, used for example in the separating device to support the discharge of the particles can be kept small, and the separating device can thus be made inexpensively.

With a high load and / or high volume flow, on the other hand, a relatively large filter area can be set, so that a high discharge quantity of the particles can be achieved.

According to a possible further development, a number of the filter elements connected to the flow of hot gas in terms of flow technology is variably set during operation of the device. It is thus possible that the filter surface can be adapted to a current load and / or a current volume flow without interrupting the operation of the device.

Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

• 1 schematisch ein erstes Ausführungsbeispiel einer Vorrichtung zur Herstellung von Partikeln und
• 2 schematisch ein zweites Ausführungsbeispiel einer Vorrichtung zur Herstellung von Partikeln.

In it show:

• 1 schematically a first embodiment of a device for producing particles and
• 2 schematically shows a second embodiment of an apparatus for producing particles.

Corresponding parts are provided with the same reference symbols in all figures.

1 shows a possible first embodiment of a device PR , in particular a thermal reactor for the production of fine particles P , in particular of nanoscale or nanocrystalline particles P , For example, they have at least one raw material RM Particles P produced in the end product have an average particle or grain size of less than 10 nm to a few millimeters.

The thermal reactor is designed, for example, as a pulsation reactor, in which in a pulsating, oscillating hot gas stream HGS the particles P be formed. For this purpose, the thermal reactor comprises a burner 1 and one goes to the burner 1 subsequent combustion chamber 2 to generate the pulsating hot gas flow HGS , This creates combustion gases VG and at least one fuel BS via a feeder 3 together or separately in the burner 1 and into the combustion chamber 2 brought in.

As fuel BS a combustible gas such as natural gas and / or hydrogen is supplied in particular. Another suitable gas can also be supplied as fuel gas.

As a combustion gas VG For example, ambient air, oxygen, etc. is used. The combustion gases supplied VG and fuels BS for example in the combustion chamber 2 ignited. The resulting flame pulsates due to self-excited, periodic, transient combustion and generates a pulsating hot gas flow HGS in the combustion chamber 2 , The pulsating hot gas flow HGS flows from the combustion chamber 2 on the flow outlet side into a reaction chamber section, for example in the form of a resonance tube 5 ,

The fuel will be in detail BS as well as the necessary combustion gas VG together, for example premixed, or separately via the burner 1 the combustion chamber 2 fed and ignited there. The fuel burns BS and the combustion gas VG very quickly and generate a pressure wave in the direction of the reaction space section 5 , Due to the lower flow resistance in the direction of the reaction space section 5 a pressure wave spreads. During the acoustic waveform, the pressure in the combustion chamber 2 reduced, so that new fuel gas mixture or new fuel BS and combustion gas VG can flow in. This process of post-flow due to pressure fluctuations takes place periodically in a self-regulating manner. The pulsating combustion process in the combustion chamber 2 generates the pulsating hot gas flow HGS , which is characterized by a high degree of turbulence. The high flow turbulence and the constantly changing flow velocity prevent the build-up of an insulating gas envelope (boundary layer) around which the raw material is made RM , in particular a raw material mixture, forming particles P , whereby a higher heat transfer and mass transfer (between raw material and hot gas), i.e. a faster reaction at comparatively lower temperatures, is possible. Typically, the dwell time is less than one second to a few seconds. In addition, a particularly large proportion of the particles P formed reaches a desired spherical shape. The rapid reaction continues to lead to the formation of the solid phase of the particles P. high proportion of lattice disorder (for example to a nanocrystalline form) and consequently to a high reactivity of the particles produced P , For the separation of the particles P as a reaction product from the hot gas stream HGS joins the reaction space section 5 at least indirectly a suitable separation device 7 for fine particles P or very fine particles.

The frequency of the pulsating hot gas flow HGS lies in the Hertz range, in particular in a range of a few Hertz, for example greater than 5 Hz, in particular greater than 50 Hz, for example in a range of 5 Hz to 350 Hz. Parameters of the hot gas flow HGS , such as the amplitude and / or frequency of the vibration, can be set. This can be done via the combustion parameters, such as the amount of fuel, amount of air, air temperature, fuel temperature and / or flame temperature, location of the fuel / air application and / or via proportions and / or changes in the combustion chamber 2 , Burner 1 and / or reaction space section 5 respectively.

The combustion chamber 2 is designed as a combustion chamber whose dimensions, in particular its diameter, are larger than the dimensions, in particular the diameter, of the reaction chamber section 5 ,

In the embodiment shown 1 are the combustion chamber 2 and the reaction space section 5 arranged substantially perpendicular to each other. Here is the combustion chamber 2 arranged essentially vertically. The reaction space section 5 is horizontal to the combustion chamber 2 arranged. However, any other suitable arrangement is also possible.

Between the combustion chamber 2 and the reaction space section 5 can be arranged an arc element which the combustion chamber 2 and the reaction space section 5 fluidly connects.

In addition, there is at least one posting location AO to abandon raw material RM , hereinafter referred to as raw material feed.

The task of the raw material RM in one possible embodiment takes place at the upper end of the combustion chamber 2 , especially at the transition from the combustion chamber 2 to the reaction space section 5 , In particular, the raw material material is used RM into the hot gas flow HGS in the direction of flow R and parallel to this.

In case of abandonment of the raw material RM , in particular a solution or a suspension, already in the combustion chamber 2 can the combustion chamber 2 form a reaction space themselves. Generally takes place in the combustion chamber 2 the combustion takes place and the generation of the pulsating hot gas flow HGS , In contrast, takes place in the reaction space section 5 usually no combustion of the fuel BS more instead. However, it is also possible, in particular at the entrance of the reaction space section 5 and thus in the area of the upper end of the combustion chamber 2 additional fuel BS and / or combustion gas VG to be fed as intermediate firing. It is also possible at the top of the combustion chamber 2 Feed raw material. In this case, the combustion chamber forms 2 also a reaction room, since material is also treated there.

The reaction space section 5 is the separation device at least indirectly, for example via an output line 7 downstream. The raw material RM is by means of the hot gas flow HGS from the place of posting AO over the reaction space section 5 forming the particles P to the separator 7 managed and transported. The separator 7 is, for example, a centrifugal separator and / or a gravity separator and / or a filter, in particular a hot gas filter. From the separator 7 the produced particles P are separated.

Operation of the separator 7 and an effort to deploy the particles P from this are dependent on a load and a volume of the hot gas flow HGS , For example, the expense of a discharge depends on the occupancy, ie a layer thickness within the separating device 7 deposited particles P on a filter medium, as this only occurs within the separator from a minimum layer thickness 7 loosen by gravity and emerge from it. With a lower occupancy, ie lower layer thicknesses, the discharge is supported, for example by a separator (not shown in more detail) 7 coupled device required.

To operate the separator 7 to a respective load and / or a volume of the hot gas flow HGS , hereinafter referred to as volume flow, to adapt, comprises the separating device 7 a filter arrangement 8th , whose filter area is variably adjustable. The filter arrangement 8th is designed such that the particles produced on the filter surface P be deposited.

In the exemplary embodiment shown, the filter arrangement comprises 8th for this variable setting of the filter surface, for example, a plurality of filter elements 9.1 to 9.n. , which are designed, for example, as so-called filter cassettes. There are a number of fluidics with the hot gas flow HGS , ie the reaction space section 5 , connected filter elements 9.1 to 9.n. variably adjustable. For this purpose, the device comprises PR for example a switching element 10 for establishing or blocking the fluidic connection between the filter elements 9.1 to 9.n. and the hot gas flow HGS ,

The switching element 10 is designed, for example, as a so-called slide, by means of which the filter elements 9.1 to 9.n. individually flow-wise with the hot gas flow HGS can be connected or blocked by this. The switching element can also 10 comprise several valves for opening or blocking the fluidic connection. Several switching elements can also be used in exemplary embodiments that are not shown in detail 10 be provided for establishing or blocking the fluidic connection.

The formation of the device PR According to the illustrated embodiment, the fluidic connection can be established or blocked during operation of the device PR , Here, the number of active filter elements 9.1 to 9.n. during the operation of the device PR by appropriate actuation of the switching element 10 can be set.

For example, a filter element can be used first 9.1 can be used for filtering or separation. You can then click on another filter element 9.2 to 9.n. are switched and the fluidic connection to the filter element used initially 9.1 is blocked. This enables the filter element initially used to be emptied and / or cleaned 9.1 without interrupting the operation of the device 1 is required. It is also possible to change the loading and / or the volume flow by means of the switching element 10 during the operation of the device PR filter elements 9.1 to 9.n. add or block to the filter surface and thus adapt the filter surface to a current load and / or a current volume flow without interrupting operation.

2 shows a possible second embodiment of a device PR , in particular a thermal reactor for the production of finely divided particles P, in particular nanocrystalline particles P. The mode of operation of the device PR corresponds to the functioning of the in 1 illustrated first embodiment of the device PR with the difference that the filter arrangement 8th the separator 7 a plurality of filter connections 11.1 to 11.M for connecting at least one filter element 9.1 to 9.n. includes.

In one possible embodiment, the filter arrangement 8th a side of the hot gas loaded with particles P is separated from a side of the pure exhaust gas by a wall. For example, there are recesses or receptacles in this wall for fastening filter elements 9.1 to 9.n. educated. Fewer filter elements for adaptation reasons 9.1 to 9.n. needed, these recesses or receptacles with specially designed locking elements 12.1 to 12.z , for example so-called blind disks or blind covers, are closed.

In the exemplary embodiment shown, the filter connections are 11.1 to 11.M for example for connecting filter elements 9.1 to 9.n. trained, which are so-called bag filters.

The filter connections include 11.1 to 11.M at least one opening each O1 to Om for inserting and removing the filter elements 9.1 to 9.n. ,

For inserting a filter element 9.1 to 9.n. For example, a housing of the separator 7 opened and the corresponding filter element 9.1 to 9.n. will be in an opening O1 to Om and at the corresponding filter connection 11.1 to 11.M connected. Removal of the filter element 9.1 to 9.n. also takes place through the corresponding opening O1 to Om. In this way it is possible by the number in the filter connections 11.1 to 11.M filter elements used 9.1 to 9.n. adjust the filter area.

To avoid the hot gas flow HGS through filter connections 11.1 to 11.M out in which no filter elements 9.1 to 9.n. are arranged and therefore no separation of the particles P openings are possible O1 to Om of the empty filter connections 11.1 to 11.M each with a closure element 12.1 to 12.z closed to block a flow through the openings O1 to Om through the loaded hot gas flow HGS to realize. The closure elements 12.1 to 12.z are designed, for example, as plugs or blind covers.

LIST OF REFERENCE NUMBERS

1

burner

2

combustion chamber

3

feed

5

Reaction chamber section

7

separating

8th

A filter assembly

9.1 to 9.n.

filter element

10

switching element

11.1 to 11.m

filter connection

12.1 to 12.z.

closure element

AO

Aufgabeort

BS

fuel

HGS

Hot gas stream

O1 to Om

opening

PR

contraption

R

flow direction

RM

Raw material material

VG

combustion gas

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 02/072471 A2 [0006]
• DE 102004044266 A1 [0006]

Claims (10)

Device (PR) for producing particles (P), in particular of finely divided, such as nanoscale or nanocrystalline particles (P), for example with an average particle size of 10 nm to a few millimeters, from at least one raw material (RM), - With at least one burner (1) and a combustion chamber (2) adjoining the burner (1) for generating a pulsating hot gas flow (HGS), - With a reaction chamber section (5) downstream of a material task and - With a separation device (7) at least indirectly connected to the reaction chamber section (5) for separating formed particles (P) from the hot gas stream (HGS), - The separating device (7) comprises a filter arrangement (8), the filter surface of which is variably adjustable. Device (PR) after Claim 1 , wherein the reaction space section (5) comprises a resonance tube. Device (PR) after Claim 1 or 2 , wherein the filter arrangement (8) comprises a plurality of filter elements (9.1 to 9.n). Device (PR) after Claim 3 , wherein a number of filter elements (9.1 to 9.n) connected to the flow of hot gas (HGS) can be variably adjusted. Device (PR) after Claim 4 , comprising at least one switching element for establishing or blocking the fluidic connection between the filter elements (9.1 to 9.n) and the hot gas flow (HGS). Device (PR) according to one of the preceding claims, - The filter arrangement (8) comprises a plurality of filter connections (11.1 to 11.m) for receiving at least one filter element (9.1 to 9.n), - The filter connections (11.1 to 11.m) each comprise at least one opening (O1 to Om) for inserting and removing the at least one filter element (9.1 to 9.n). Device (PR) after Claim 6 , comprising a plurality of closure elements (12.1 to 12.z) for closing the openings (O1 to Om) and / or for blocking a flow through the filter elements (9.1 to 9.n) by the loaded hot gas stream (HGS). Device (PR) according to one of the preceding claims, wherein the filter elements (9.1 to 9.n) are designed as a bag filter. Process for the production of particles (P), in particular of finely divided, such as nanoscale or nanocrystalline particles (P), for example with an average particle size of 10 nm to a few millimeters, from at least one raw material (RM) by means of a device (PR) according to one of the preceding claims, the filter area of the filter arrangement (8) of the separating device (7) being variably set as a function of a load and / or a volume of the hot gas stream (HGS). Procedure according to Claim 9 , A number of filter elements (9.1 to 9.n) connected to the hot gas flow (HGS) in terms of flow technology being variably set during operation of the device (PR).

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